Package Exports

@well-known-components/metrics
@well-known-components/metrics/dist/index.js

This package does not declare an exports field, so the exports above have been automatically detected and optimized by JSPM instead. If any package subpath is missing, it is recommended to post an issue to the original package (@well-known-components/metrics) to support the "exports" field. If that is not possible, create a JSPM override to customize the exports field for this package.

Readme

metrics

npm i @well-known-components/metrics

Configuration via config component

Here is a list of configuration keys that may be used by this component:

WKC_METRICS_PUBLIC_PATH: string path to expose metrics, default: /metrics
WKC_METRICS_BEARER_TOKEN: string bearer token to protect metrics, default: not set
WKC_METRICS_COLLECT_DEFAULT: "true" | "false" collect default nodejs metrics, default: true
WKC_METRICS_RESET_AT_NIGHT: "true" | "false" resets all user-defined metrics every day at 00.00 UTC, default: false

Define your metrics in a static file

// src/metrics.ts

import { IMetricsComponent } from "@well-known-components/interfaces"
import { validateMetricsDeclaration } from "@well-known-components/metrics"

export const metricDeclarations = {
  // register all http-server metrics
  ...getDefaultHttpMetrics(),
  // IMetricsComponent.SummaryType
  // IMetricsComponent.HistogramType
  // IMetricsComponent.GaugeType
  // IMetricsComponent.CounterType
  user_counter: {
    type: IMetricsComponent.CounterType,
    help: "Count calls to /user/:userId",
    labelNames: ["userId"],
  },
}

// type assertions
validateMetricsDeclaration(metricDeclarations)

Define the component

// src/components.ts

import { metricDeclarations } from "./metrics"

export async function initComponents(): Promise<AppComponents> {
  ...
  // const config
  // const server
  const metrics = await createMetricsComponent(metricDeclarations, {config})
  await instrumentHttpServerWithMetrics({ metrics, config, server })

  return { ...components, metrics }
}

Register metrics

export async function userIdHandler(context: { components: Pick<AppComponents, "metrics"> }) {
  const {
    components: { metrics },
  } = context

  metrics.increment("user_counter", { userId: Math.random() })
  // metrics.decrement("user_counter", { userId: Math.random() })
  // metrics.observe("user_counter", { userId: Math.random() }, 1)
  // metrics.reset("user_counter")

  return {}
}

Migrating from 1.0.0 to 2.0.0

A few things must be taken into account since it is a breaking change

The metrics component does not automatically instrument an http server, it should be done manually via instrumentHttpServerWithMetrics
And thus, the default metricsDeclaration also don't include the default http metrics, it can be composed with those metrics via metricsDeclaration = { ...getDefaultHttpMetrics(), ...yourMetrics }